Manufacture of commutators.



C. W. DUNHAM.

MANUFACTURE OF COMMUTATOHS. APPLICATION FILED MAR-16.1911.

1,233,764. Patented July 17, 1917.

gwm n j. 1' I WWW M m W UNITED STATES PATENT OFFICE.

CHARLES DUNHAM, OF EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNIONSWITCH & SIGNAL COMPANY, OF'SWISSVALE, PENNSYLVANIA, A CORPORA- TI ON OFPENNSYLVANIA.

' MANUFACTURE OF COMMUTATORS.

Application filed March 16, 1917. Serial No. 155,260.

I will discuss one method of manufacture embodying my invention, andwill then' point out the novel featuresthereof in claim.

In the accompanying drawings, Figure 1 is a view showing in perspectivea metal blank, from which the commutator is to be made. Fig. 2 is a viewshowing this blank in end elevation after the first operations have beenperformed thereon. Fig. 3 is a sectional view on the line III-III ofFig. 2, showing also a mandrel in place in the blank, the blank nowbeing ready for the application of insulatin material. Fig. 1 is an endelevation showing the blank with the insulating material therein, andFig. 5 is a sectional view on the line VV of Fig. 4. Fig. 6 is a viewsimilar to Fig, 5 but showing the commutator in finished condition.

Similar reference characters refer to similar parts in each of theseveral views.

Referring first to Fig. 1, the reference character 10. designates ablank of electroeonductive material, preferably copper, in the form of acylindrical block. This block is first provided with a central axialbore 11 (Figs. 2 and 3) the diameter of which is greater than that ofthe shaft on which the commutator is to be mounted. Each end of theblock is then countersunk to form recesses 12, 12% the recess 12 beingsomewhat deeper than recess 12. The next operation consists in cuttingradial slots 13 in the blank, each slot extending from the central boret0 the outer circumference, and from one end of the blank to a plane 13near the Specification of Letters Patent.

Patented July 17, 1917.

other end. These slots thus divide the blank Into segments 14 which areunited by a ring of metal 15.

A mandrel 16 is then placed in the axial bore 11, this mandrel being ofthe same diameter as the shaft uponwhich the commutator is to bemounted. The blank and mandrel are next placed in a suitable receptaclewherein lnsulating material may be forced under pressure into the slots13 and into the space betwee the mandrel and the central bore. Theinsulating material may be of an suitable kind, such, for example, as ba(elite. During this step in the process, the blank and mandrel are, ofcourse, held firmly in such positions that the axes of the two coincide.

After the insulating material has hardened or set,the mandrel iswithdrawn, leaving the device in the condition in which it is shown inFigs. 1 and 5, the insulating material being designated 17. Thecommutator is then completed by removing the ring 15 of metal,preferably by machining, so that the segments are completely insulatedfrom each other. The commutator in this completed condition isillustrated in section in Fig. 6. When the commutator is placed on themotor or insulated, of course, from the shaft by the ring of insulatingmaterial in the axial bore of the commutator.

One important feature of this method of manufacture is that theinsulating material for the entire commutator is molded in place at onetime, that is, by the one step in the process the segments are insulatedfrom each other and from the commutator shaft.

Having thus described my invention, what claim is:

The method of manufacturing commutators which consists in producing acylindrical blank having an axial bore larger than the shaft on to bemounted, cutting radial slots in said blank extending from the outer thebore, and from one end bore a mandrel generator shaft, each segment willbe surface to which the commutator is substantially of the same size asthe shaft on which the commutator is to be mounted, fillingthe slots andthe space between the mandrel and the bore with insulating material, andsubsequently removing the mandrel and cutting off the solid end of theblank.

In testimony whereof I afiix my signature in presence of two witnesses.I

CHARLES W. DUNHAM. Witnessesz' A. HERRMAN WEGNER, R. GEORGE RUDMAN.

